Aircraft landing gear and aircraft wheels are typically equipped with brakes in order to stop an aircraft after landing or during a rejected take-off braking stop. Generally, a braked wheel can be described as experiencing one of four conditions; unbraked (synchronous speed), braked but not skidding (slip velocity less than critical value), skidding (slip velocity greater than critical value), or fully locked.
Historically, prior to landing, having prior knowledge of various runway conditions was not possible. Accordingly, without prior knowledge of runway conditions, brake control systems had to expend time to assess runway conditions and enact operation during braking. This time to assess braking conditions and change performance resulted in a reduction in braking performance and the potential increase to stop distances.